Researchers develop tiny probe for intravascular imaging in the brain

25 August 2026

Researchers develop tiny probe for intravascular imaging in the brain

WASHINGTON - Researchers have developed a tiny optical imaging probe designed for optical coherence tomography (OCT) imaging inside blood vessels in the brain. With further development, the tiny probe - which is about the width of a pencil lead and the length of a grain of rice - could be used to acquire detailed information about vascular disease and devices such as stents implanted in the brain.

"Doctors currently have limited tools for looking at microscopic details directly inside small and tortuous brain arteries," said Rui Liu, who led the research team from the Medical School of Nanjing University in China. "Measuring just 0.55 mm in diameter and 4 mm long, our new probe is designed to fit inside these arteries and acquire full 360-degree images by using a tiny piezoelectric actuator to rotate an optical lens."

In the Optica Publishing Group journal Biomedical Optics Express, the researchers show that the probe can navigate through a full-scale human cerebrovascular model to reach the middle cerebral artery, one of the major arteries in the brain. They also demonstrate that it can image vascular stents, blood-vessel structures and excised human atherosclerotic plaque tissue.

"Although the probe would need more development and testing to be used clinically, intravascular OCT could one day give physicians a much closer look at what is happening inside the small arteries of the brain," said Dawei Wu, who led the research team from the Nanjing University of Aeronautics and Astronautics. "For example, it could provide a detailed view of how a stent is positioned relative to the vessel wall, potentially helping doctors make better treatment decisions and provide safer, more personalized care."

Bringing OCT into the brain

OCT is a light-based imaging technique that produces detailed, cross-sectional images of tissue, making it useful for visualizing the structure of blood vessel walls and detecting changes such as plaque buildup.

However, most existing intravascular OCT systems were developed for coronary arteries, which are generally larger and have fewer bends and twists than the small arteries in the brain. These systems typically use a motor outside the body to rotate the optical probe. When a long imaging catheter passes through the smaller, more curved vessels of the brain, friction and twisting can cause the probe to rotate unevenly, producing imaging distortion known as nonuniform rotational distortion.

One solution is to put a very small motor directly at the tip of the catheter. However, conventional electromagnetic micromotors become difficult to miniaturize below about one millimeter, and their electrical wires can block part of the optical field of view.

"We wanted to develop a fundamentally different miniature drive mechanism that could be placed at the distal tip of the catheter, remain extremely small, and still provide an unobstructed 360-degree optical scan," said Liu. "By rotating the lens directly at the catheter tip, we can also avoid the rotational distortion that can occur when a long catheter is rotated from outside the body."

The probe they designed works essentially like a microscopic rotating camera inside a blood vessel. At the center of the probe is a tiny optical fiber that carries near-infrared light to a miniature angled lens. Instead of rotating the entire catheter from outside the body, only this tiny lens on the tip of the catheter is rotated.

The rotating motion comes from a piezoelectric material, which changes shape slightly when an electrical voltage is applied. As the lens rotates, it directs the OCT light around the entire inner wall of the vessel, making it possible to collect a complete 360-degree cross-sectional image. By gradually moving the probe along the vessel, many cross-sectional images can also be combined into a 3D view.

Testing the probe with tiny turns

The researchers tested the new probe by first evaluating the uniformity of its 360-degree scanning by imaging four metal tubes arranged at known angles. The measured angular deviation was only about one degree, demonstrating highly uniform circumferential scanning even after the catheter had traveled through the tortuous vascular model. They also showed that the lens can rotate rapidly, reaching speeds of up to 58 revolutions per second.

They then used the probe to produce 2D and 3D OCT images of several increasingly complex samples, including the fine vein network of a magnolia leaf, a vascular stent positioned in a middle cerebral artery model and an ex vivo porcine blood vessel.

They also used the probe to acquire OCT images of excised human atherosclerotic plaque tissue, which they compared with conventional histological examination. The optical images showed features associated with lipid-rich regions and fibrotic tissue, observations that were consistent with the histological findings.

Future work will focus on making the probe smaller, improving its optical resolution and imaging depth, and increasing the stability and speed of the rotating lens. The researchers note that before the probe can be used for clinical applications, the technology will need further testing to confirm its imaging performance, reliability and safety under conditions that more closely match actual neurointerventional procedures.

Paper: B. Wang, X. Liu, H. Yu, K. Tao, R. Liu, D. Wu, "Neurointerventional optical coherence

tomography using a piezo-driven microprobe," Biomed. Opt. Express, 17, 4726-4740 (2026).

DOI: 10.1364/BOE.606116

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About Biomedical Optics Express

Biomedical Optics Express serves the biomedical optics community with rapid, open-access, peer-reviewed papers related to optics, photonics and imaging in biomedicine. The journal scope encompasses fundamental research, technology development, biomedical studies and clinical applications. It is published monthly by Optica Publishing Group and edited by Ruikang (Ricky) Wang, University of Washington, USA. For more information, visit Biomedical Optics Express.

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